Question

Statistics Canada reports that the birth weight of newborn babies in Saskatchewan has a mean of 3.45 kg for both sexes.
Suppose the standard deviation is 0.7 kg. Further we randomly sample 49 birth certifi- cates in Saskatchewan and record the birth weights of samples babies. Find the mean and standard deviation of the sampling distribution of x ̄. What is the probability that sample mean birth weight will be less than 3.25 kg?

Answer 1

Solution :

Given that ,

mean = = 3.45

standard deviation = = 0.7

n = 49

= = 3.45   

= / n = 0.7 / 49= 0.1

P( < 3.25 ) = P(( - ) / < (3.25 - 3.35) / 0.1 )

= P(z < - 1 )

Using z table

= 0.1587